Questions and Answers
What is a potential treatment option for defects in the purine salvage pathway?
Which enzyme replacement therapy is applicable for adenosine deaminase deficiency?
Which of the following is a key clinical manifestation in a patient with adenosine deaminase deficiency?
Which of the following purines is comprised of a nitrogenous base?
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What clinical symptom may suggest immunodeficiency in a child?
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What is a characteristic physical examination finding in a 6-month-old with adenosine deaminase deficiency?
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Which diagnosis might be considered in a child presenting with decreased sensorium and hepatosplenomegaly?
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In the context of adenosine deaminase deficiency, what is the primary metabolic consequence of the condition?
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What is the primary cause of gout in patients with Lesch-Nyhan syndrome?
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Which joint is most commonly affected in patients with gout?
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How does hyperuricemia contribute to urate crystal formation?
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What is the inheritance pattern of Lesch-Nyhan syndrome?
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What primary symptom progresses from mono-arthritis to polyarthritis in gout?
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What metabolic deficiency is linked to Lesch-Nyhan syndrome?
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Which aspect of temperature is relevant in urate crystal formation in extremities?
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Which of the following conditions can contribute to hyperuricemia?
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What is the role of 5-phosphoribosyl-1-pyrophosphate (PRPP) synthetase in inflammation?
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Which condition is characterized by the crystallization of uric acid in the joints?
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What is the primary consequence of increased purine nucleotide degradation?
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What clinical condition is associated with elevated uric acid levels?
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Which syndrome is linked to defects in the purine salvage pathway?
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What is a common symptom associated with the presence of urate crystals in the joints?
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How does inflammation affect pH levels in the affected area?
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What is the impact of hyperuricemia on joint health?
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What is a primary mechanism of action for colchicine in treating gout?
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Which condition would likely lead to the use of uricosuric agents like probenecid?
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What typical side effect is associated with colchicine?
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What is the normal serum uric acid level indicated for gout diagnosis?
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What diagnostic finding is associated with gout during arthrocentesis?
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What is a likely consequence of urate crystals rupturing phagocytes in gout?
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In the purine catabolic pathway, what enzyme's activity is inhibited by allopurinol?
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Which of the following is not true regarding colchicine?
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What is the primary reason why uric acid can crystallize in the blood?
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What role does the salvage pathway play in purine metabolism?
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How does allopurinol function in treating gouty arthritis?
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What is the primary metabolic issue associated with gouty arthritis?
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What physiological state can lead to the crystallization of uric acid?
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What is the chemical form of uric acid present in blood under physiological conditions?
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What is the most likely trigger for the acute attack of gout in the presented case?
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What is the role of colchicine in managing gout symptoms?
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Study Notes
Overproduction and Clinical Manifestations
- De novo synthesis of purines is a critical metabolic pathway involved in nucleotide production.
- Defects in the purine salvage pathway can lead to various disorders, including adenosine deaminase (ADA) deficiency and Lesch-Nyhan syndrome.
- Inflammation from uric acid crystal deposition leads to conditions like gout.
- Clinical presentations include immunocompromised states reflected by decreased sensorium, hepatosplenomegaly, lethargy, and joint pain.
Case Studies
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Case No. 1: Adenosine Deaminase Deficiency
- Presents in a 6-month-old with lethargy, low appetite, and unresponsive diaper rash.
- Symptoms of frequent upper respiratory tract infections and hypotonia noted.
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Case No. 2: Gouty Arthritis
- 43-year-old male experienced sudden, severe right big toe pain after excessive drinking.
- Gout results from high uric acid levels leading to sodium urate crystal formation in joints, causing swelling and tenderness.
Purine Metabolism
- Impairments in purine metabolism result in hyperuricemia and gout, with uric acid being toxic at high levels.
- Uric acid is poorly soluble, leading to crystallization when blood saturation exceeds normal levels.
- Disturbances in purine nucleotide production directly link to increased uric acid output.
Treatment Options
- Potential treatments include haploidentical bone marrow transplantation, ADA enzyme replacement therapy, and ADA gene therapy for ADA deficiency.
- For gout management, medications like allopurinol (xanthine oxidase inhibitor) and colchicine (inhibits microtubule formation) are used.
- Uricosuric agents, such as probenecid, enhance uric acid excretion in patients with underexcretion.
Clinical Correlations
- Lesch-Nyhan syndrome is a genetic condition associated with mental retardation and self-destructive behavior; related to reduced purine salvage.
- Gouty arthritis primarily affects the metatarsophalangeal joint; rapid onset of symptoms can indicate a gout flare.
- Diagnosis of gout relies on the detection of negatively birefringent urate crystals in synovial fluid.
Diagnostic Tests
- Elevated serum uric acid levels signal potential gout; however, levels may normalize during acute attacks.
- Urinary uric acid excretion over 800 mg per 24 hours is indicative of conditions related to uric acid metabolism.
- Arthrocentesis can reveal characteristic crystal formations aiding in gout diagnosis.
Summary of Mechanisms
- Microtubule inhibition by colchicine reduces inflammatory responses in joints.
- Increased activity of 5-phosphoribosyl-1-pyrophosphate (PRPP) synthetase promotes purine synthesis, exacerbating conditions related to uric acid excess.
- Uric acid crystals preferentially form in cooler extremities, contributing to gout pathophysiology.
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Description
This quiz explores the clinical implications of purine metabolism disorders, including adenosine deaminase deficiency and gout. Case studies highlight symptoms and presentations, illustrating the impact of purine overproduction on health. Test your knowledge on these critical metabolic pathways and their disorders.
